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// This Source Code is in the Public Domain per: http://litesoft.org/License.txt package org.litesoft.core; import java.util.*; import org.litesoft.core.typeutils.*; public class ClassToInstanceMapperImpl implements ClassToInstanceMapper { public ClassToInstanceMapperImpl() { } private Map<Class<?>, NoInstanceFactory<?>> mFactoriesByClass = new HashMap<Class<?>, NoInstanceFactory<?>>(); private Map<Class<?>, Object> mInstanceByClass = new HashMap<Class<?>, Object>(); /** * Get a List (!null) of all the currently "set" Factories */ public synchronized List<NoInstanceFactory<?>> getNoInstanceFactories() { return new ArrayList<NoInstanceFactory<?>>( mFactoriesByClass.values() ); } /** * Set a Factory into this Mapper. This Factory is used to create an Instance (and register it) when "get" is called and no Instance is currently registered. * * @param pFactory !null * * @throws IllegalArgumentException if pFactory is null * @throws IllegalStateException if this is a duplicate Factory */ public void setNoInstanceFactory( NoInstanceFactory<?> pFactory ) { Objects.assertNotNull( "NoInstanceFactory", pFactory ); Class<?> zClass = pFactory.getFor(); assertClass( zClass ); synchronized ( this ) { NoInstanceFactory<?> zFactory = mFactoriesByClass.get( zClass ); if ( zFactory == null ) { mFactoriesByClass.put( zClass, pFactory ); return; } } throw new IllegalStateException( "Duplicate Factory for: " + zClass ); } /** * @param pClass !null * * @return null if not found or current instance set / replaced * * @throws IllegalArgumentException if pClass is null */ public <T> T checkGet( Class<T> pClass ) throws IllegalArgumentException { assertClass( pClass ); synchronized ( this ) { //noinspection unchecked return (T) mInstanceByClass.get( pClass ); } } /** * Get the previously 'registered' (set &/ replaced) instance of pClass. * NOTE: if there is no instance currently registered, then one is attempted to be added using a previously registered NoInstanceFactory. * * @param pClass !null * * @return instance of pClass * * @throws IllegalArgumentException if pClass is null * @throws IllegalStateException if no instance previously 'registered' for pClass */ public <T> T get( Class<T> pClass ) throws IllegalArgumentException, IllegalStateException { assertClass( pClass ); Object zInstance; synchronized ( this ) { if ( null == (zInstance = mInstanceByClass.get( pClass )) ) { NoInstanceFactory<?> zFactory = mFactoriesByClass.get( pClass ); if ( zFactory != null ) { if ( null != (zInstance = zFactory.createInstance()) ) { mInstanceByClass.put( pClass, zInstance ); } } } } if ( zInstance == null ) { throw new IllegalStateException( "No instance found for: " + pClass ); } //noinspection unchecked return (T) zInstance; } /** * Set or register an instance (pInstance) of pClass, that is NOT currently 'registered' (previously set &/ replaced, but not subsequently removed) * * @param pClass !null * @param pInstance !null * * @throws IllegalArgumentException if either pClass or pInstance is null * @throws IllegalStateException if an instance for pClass IS currently 'registered' */ public <T, V extends T> void set( Class<T> pClass, V pInstance ) throws IllegalArgumentException, IllegalStateException { assertClassAndInstance( pClass, pInstance ); synchronized ( this ) { Object zInstance = mInstanceByClass.get( pClass ); if ( zInstance == null ) { mInstanceByClass.put( pClass, pInstance ); return; } } throw new IllegalStateException( "Already an instance for: " + pClass ); } /** * Replace or re-register an instance (pInstance) of pClass, that IS currently 'registered' (previously set &/ replaced, but not subsequently removed) * * @param pClass !null * @param pInstance !null * * @throws IllegalArgumentException if either pClass or pInstance is null * @throws IllegalStateException if an instance for pClass is NOT currently 'registered' */ public <T, V extends T> void replace( Class<T> pClass, V pInstance ) throws IllegalArgumentException, IllegalStateException { assertClassAndInstance( pClass, pInstance ); synchronized ( this ) { Object zInstance = mInstanceByClass.get( pClass ); if ( zInstance != null ) { mInstanceByClass.put( pClass, pInstance ); return; } } throw new IllegalStateException( "No instance to replace for: " + pClass ); } /** * Remove the instance (pInstance) of pClass, that IS currently 'registered' (previously set &/ replaced, but not subsequently removed) * * @param pClass !null * @param pInstance !null * * @throws IllegalArgumentException if either pClass or pInstance is null * @throws IllegalStateException if pInstance of pClass is NOT currently 'registered' for pClass */ public <T, V extends T> void remove( Class<T> pClass, V pInstance ) throws IllegalArgumentException, IllegalStateException { assertClassAndInstance( pClass, pInstance ); Object zInstance; synchronized ( this ) { zInstance = mInstanceByClass.get( pClass ); if ( pInstance == zInstance ) { mInstanceByClass.remove( pClass ); return; } } if ( zInstance == null ) { throw new IllegalStateException( "No instance currently exists for: " + pClass ); } throw new IllegalStateException( "Instance to remove '" + pInstance + "' mismatchs found '" + zInstance + "' for: " + pClass ); } public synchronized void clearAllInstances() { mInstanceByClass.clear(); } private void assertClass( Class<?> pClass ) { Objects.assertNotNull( "Class (key)", pClass ); } private void assertClassAndInstance( Class<?> pClass, Object pInstance ) { assertClass( pClass ); Objects.assertNotNull( "pInstance (value)", pInstance ); } } |